Crystal Lab › Prototype structures › Tetragonal
Zr₃Al₂
Tetragonal · space group P42/mnm (No. 136) · Pearson tP20
Symmetry elements and Wyckoff positions (interactive)
Zr₃Al₂ in P42/mnm
SettingUnit cell
- Lattice constants
- a = 7.630 Å, b = 7.630 Å, c = 6.998 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 407.4 ų
- Atoms in the conventional cell
- 20 (Zr 12, Al 8)
- Formula units Z
- 4
- Pearson symbol
- tP20 — tetragonal, primitive lattice, 20 atoms per conventional cell
- Symmetry operations
- 16 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Zr2 | Zr | 4d | 4 | 0.0000 | 0.5000 | 0.2500 |
| Zr3 | Zr | 4f | 4 | 0.3400 | 0.3400 | 0.0000 |
| Zr4 | Zr | 4g | 4 | 0.2000 | 0.8000 | 0.0000 |
| Al1 | Al | 8j | 8 | 0.1250 | 0.1250 | 0.2100 |
The multiplicity and the Wyckoff letter say how many copies of the site the group makes in one cell and on which kind of symmetry element the site sits; the 20 atoms drawn above are these sites multiplied by all 16 operations. Press Wyckoff under Colour to see the sites, and tick a symmetry element on the left to see which atoms lie on it.
How to read the label
A2B3_tP20_136_j_dfg-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol tP20, then the space-group number 136, then the Wyckoff letters occupied by each element in turn (Zr: 4d; Zr: 4f; Zr: 4g; Al: 8j). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
Dy₃Al₂, Er₃Al₂, Ga₃Hf₂, Ga₃Zr₂, Gd₃Al₂, Hf₃Al₂, Ho₃Al₂, Tb₃Al₂, Y₃Al₂ <!--beginning with an
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B3_tP20_136_j_dfg-001 (M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017); D. Hicks et al., ibid. 161, S1 (2019) and 199, 110450 (2021); S. Eckert et al., ibid. 240, 112988 (2024)). Symmetry elements, Wyckoff assignment and the diagram are computed on this page from the group operations.
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